um and aah

um and ah

To be hesitant or indecisive, especially when speaking out loud about a decision. "Um" and "ah" are common filler words used by habit or when one is deciding what to say. Try not to um and ah so much when you're considering a counter-proposal—it's not professional. It felt like that guy ummed and ahed for five minutes before he gave me his order.
See also: ah, and, um
Farlex Dictionary of Idioms.

ˌum and ˈaah (about something)

(also ˌhum/ˌhem and ˈhaw less frequent) (informal) speak but say nothing important because you need more time to think about a problem, matter, etc: He ummed and aahed for about half an hour and then finally said he would lend me the money. After a lot of umming and aahing, he finally said yes to the plan.
Um, aah, etc. are sounds that people make when they hesitate or do not know what to say next.
See also: aah, and, um
Farlex Partner Idioms Dictionary
See also:
  • aah
  • um and ah
  • you know
  • mealy
  • mealy-mouthed
  • make a habit of
  • make a habit of (doing something)
  • make a habit/practice of something
  • loose lip(s)
  • have a loud mouth
References in periodicals archive
"I did um and aah about it a bit, and we were going to bat first," he confirmed.
Anderson - I've bowled better; Lancs pace ace helps inspire win
YOU'RE not being too tongue-tied if you um and aah while talking.
WHY IT'S OKAY TO LIKE, ER, YOU KNOW.. HESITATE; Linguists say it's um, essential